The reduction of unintended adolescent pregnancy is a goal of Healthy People 2010. Yet pregnancy prevention programs for adolescents have shown limited effectiveness to date. An understanding of the psychological processes that lead to adolescent pregnancy would allow development of more effective prevention programs. Social comparison (comparing one?s self to other people) is a psychological process that may have significant implications for adolescent pregnancy prevention. The primary aim of this study is to develop an instrument-Social Comparison Uses Scale (SCUS) to describe adolescents? uses of social comparisons related to pregnancy prevention. A secondary aim is an exploratory examination of the relationships between adolescents? uses of social comparisons, stage of behavioral change for abstinence and contraceptive behavior, and behavioral self-esteem. In Part I eight focus groups (N=64) of 9th-grade (13-15 years old) adolescents will be recruited from public high school health education classes. Student populations from both high schools in the study are predominantly Hispanic and non-Hispanic white. Dimensions for the SCUS, as defined in the model for instrument development, will be confirmed or modified and items will be developed using content analysis of focus group data. The items will be assessed by five content validity experts and then pilot-tested with 40 9th-grade students. In Part II, the preliminary 40-item SCUS will be administered to 450 9th and 10th-graders from a public high school to determine reliability and further evidence of validity. Cronbach?s alpha will be used to estimate reliability. Construct validity will be examined using common factor analysis with orthogonal rotation. Concurrent validity will be assessed by comparing the SCUS with the INCOM, a measure of the tendency to make social comparisons. Exploratory comparisons of the reliability and factor structure of the SCUS across ethnic, gender, and age (9th and 10th grade) groups will be made. In Part III, the replicability of reliability and validity for the final 20-item SCUS will be tested with 250 9th and 10th-graders from a second, more high risk, public high school. Confirmatory factor analysis with Procrustes rotation will examine the congruencies of the factor structures. Exploratory comparisons of the reliability and factor structure across subgroups will again be made. Exploratory analyses of the study hypotheses will be conducted. The development of the SCUS is Phase II of a three-phase program of nursing research. In the future, the SCUS will be used to develop and test nursing interventions (based on an understanding of the use of social comparisons) that facilitate positive self-change efforts by adolescents in the area of pregnancy prevention.